More than 830,000 adults present to acute care facilities each year for treatment of acute coronary syndrome (ACS): (1) ST elevation myocardial infarction (STEMI), (2) non-ST elevation MI (NSTEMI), and (3) unstable angina (UA). Among the three, NSTEMI/UA are nearly four times more common than STEMI. Management of ACS is aimed at stabilization of a ruptured plaque in order to prevent cellular death. Recent studies, in patients with NSTEMI/UA, suggest that an early invasive strategy (percutaneous coronary interventions [PCI/stent]) might not be better than management with medications alone. There are conflicting results comparing the two treatment pathways. Treatment decisions for NSTEMI/UA are based largely on symptoms and intermittent electrocardiograms (ECG) or treadmill tests. However, because of the dynamic and unpredictable nature of coronary blood flow in NSTEMI/UA, identifying high risk patients who may require additional treatment is a substantial challenge. Therefore, innovative approaches, preferably non-invasive, are needed. Continuous 12- lead ECG monitoring, both inexpensive and non-invasive, can identify transient episodes of myocardial ischemia, a precursor to MI, even when asymptomatic. However, continuous 12-lead ECG monitoring is not usual nursing practice, rather only two leads are typically monitored;hence ischemia is likely to be missed. Therefore, the purpose of the COMPARE Study: electroCardiographic evaluatiOn of ischeMia comParing invAsive to phaRmacological trEatment) study is to assess the frequency and potential clinical consequences of transient myocardial ischemia (TMI), using 12-lead ECG monitoring, in patients with NSTEMI/UA treated with an early invasive (PCI/stent) versus those managed with medications alone. Continuous 12-lead ECG Holter monitoring will be obtained in 248 subjects (124 early invasive and 124 pharmacologic only) to detect TMI among hospitalized patients with NSTEMI/UA. The ECG data will be evaluated for TMI frequency and characteristics (ST direction, number of ECG leads, location, and duration). Outcomes (arrhythmias requiring intervention, hemodynamic compromise, pulmonary edema, unplanned transfer to intensive care, death, and infarction) will be assessed at hospital discharge. This study will provide a foundation for the development of a larger study to test whether incorporating ECG information during hospitalization for ACS can be used in deciding treatment pathways of patients presenting with NSTEMI/UA. The proposed study is directly relevant to the National Institute of Nursing Research's Strategies for Building the Science related to adopting, adapting and generating new technologies for better health care. Results from this study could potentially lead to modifications of current ECG technologies, which could ultimately help clinicians improve care delivered and reduce morbidity and mortality in patients. PUBLIC HEALTH RELEVANCE: More than 830,000 adults present to acute care facilities each year for treatment of acute coronary syndrome;(1) ST elevation myocardial infarction [STEMI], (2) non-ST elevation MI [NSTEMI], and (3) unstable angina [UA]), with NSTEMI/UA being four times more common than STEMI. There is considerable debate among clinicians regarding the best treatment pathway for NSTEMI/UA patients, early invasive (percutaneous coronary intervention/stent) versus aggressive pharmacological management alone. The use of 12-lead electrocardiographic (ECG) data, which is both inexpensive and non-invasive, should be assessed for its value in identifying high risk patients in each of these groups who may benefit from more aggressive treatment.